BUG: KASAN: use-after-free in irq_bypass_register_consumer+0x4f0/0x500 virt/lib/irqbypass.c:198
Read of size 8 at addr ffff8801d97e0178 by task syzkaller672256/14962

CPU: 0 PID: 14962 Comm: syzkaller672256 Not tainted 4.13.0-rc5+ #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 irq_bypass_register_consumer+0x4f0/0x500 virt/lib/irqbypass.c:198
 kvm_irqfd_assign arch/x86/kvm/../../../virt/kvm/eventfd.c:417 [inline]
 kvm_irqfd+0x137a/0x1d50 arch/x86/kvm/../../../virt/kvm/eventfd.c:572
 kvm_vm_ioctl+0x1079/0x1c40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3029
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x44a999
RSP: 002b:00007fa51cc29d08 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000044a999
RDX: 0000000020025fe0 RSI: 000000004020ae76 RDI: 0000000000000333
RBP: 0000000000000086 R08: 00007fa51cc2a700 R09: 00007fa51cc2a700
R10: 00007fa51cc2a700 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe0eeab99f R14: 00007fa51cc2a9c0 R15: 0000000000000000

Allocated by task 14962:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x12f/0x740 mm/slab.c:3627
 kmalloc include/linux/slab.h:493 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 kvm_irqfd_assign arch/x86/kvm/../../../virt/kvm/eventfd.c:296 [inline]
 kvm_irqfd+0x16c/0x1d50 arch/x86/kvm/../../../virt/kvm/eventfd.c:572
 kvm_vm_ioctl+0x1079/0x1c40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3029
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 3155:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xca/0x250 mm/slab.c:3820
 irqfd_shutdown+0x13c/0x1a0 arch/x86/kvm/../../../virt/kvm/eventfd.c:148
 process_one_work+0xbf3/0x1bc0 kernel/workqueue.c:2097
 worker_thread+0x223/0x1860 kernel/workqueue.c:2231
 kthread+0x35e/0x430 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:425

The buggy address belongs to the object at ffff8801d97e0000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 376 bytes inside of
 512-byte region [ffff8801d97e0000, ffff8801d97e0200)
The buggy address belongs to the page:
page:ffffea000765f800 count:1 mapcount:0 mapping:ffff8801d97e0000 index:0x0
flags: 0x200000000000100(slab)
raw: 0200000000000100 ffff8801d97e0000 0000000000000000 0000000100000006
raw: ffffea000697c1a0 ffffea00076430a0 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d97e0000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d97e0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801d97e0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff8801d97e0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d97e0200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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